Endocardial irrigated catheter for volumetric optoacoustic mapping of radio-frequency ablation lesion progression.

Radiofrequency (RF) catheter ablation is widely employed for various minimally invasive procedures, including treatment of tumors, cardiac arrhythmias and varicose veins. Accurate real-time monitoring of the ablation treatments remains challenging with the existing clinical imaging modalities due to the lack of spatial or temporal resolution or insufficient tissue contrast for differentiating thermal lesions. Optoacoustic (OA) imaging has been recently suggested for monitoring temperature field and lesion progression during RF interventions. However, strong light absorption by standard metallic catheters hindered practical implementations of this approach. Herein, we introduce a new RF ablation catheter concept for combined RF ablation and OA lesion monitoring. The catheter tip encapsulates a multimode fiber bundle for OA excitation with near-infrared (NIR) light, whereas the electric current is conducted through the irrigation solution, thus avoiding direct exposure of the metallic parts to the excitation light. We optimized the catheter diameter and the saline flow rate in order to attain uniform and deep lesions. The newly introduced hybrid catheter design was successfully tested by real-time monitoring of the ablation process in smooth ventricle and rough atrium walls of a blood-filled ex vivo porcine heart, mimicking in vivo conditions in the clinical setting.